AN/VRC-12 and AN/VRC-43 through VRC-49 is a series of
combat-proven vehicular radio sets which lend themselves
particularly well to applications of tactical deployment
and specific operational missions because of their
ability to be assembled into various configurations and
of being installed on most types of military vehicles;
including heavy armour. The equipment provides 920 VHF/FM
voice channels in the 30-76 MHz range. It consists of
three major units: Receiver-Transmitter RT-246A/VRC with
a channel-presetting capability (10 pushbuttons), Manual
Receiver-Transmitter RT-524A/VRC with built-in
loudspeaker, and Auxiliary Receiver R-442A/VRC.
In addition to the conventional noise-operated squelch, an advanced tone-operated squelch (150 Hz) is provided in this series, thus eliminating "false alarms" or undesired audio output from the receiver when net stations are not called. The tone squelch also ensures reliable retransmission when two receiver-transmitter are used as an automatic relay station in high-density communication centers where off-frequency signals often cause false triggering of the retransmission set-up.
The shown installation is known as a AN/VRC-47 set. It consists of a RT-524A/VRC (receiver/transmitter) and a R-442A/VRC (receiver).
The RT-524A/VRC is a FM Receiver-transmitter, working in the 30-75.95 MHz range with 50 kHz spacing between its 920 channels. Its a manual tuning version of the RT-246A/VRC, has a built-in speaker, and a power output of 8W (low)/35W (high).
Effective range is approx. 10 km (low) and 30 km (high).
The R-442A/VRC is a receiver working in the 30-75.95 MHz range and has 920 channels.
Both radios are powered by 24 V DC.
Some components in the Danish installation are standard (e.g. MT-1029 mounting tray) and some were produced locally (e.g. antenna mount) and have been hard tracking down. The mounting frames and plates placed on the top rear fenders had to be reproduced as no were available.
|Mounting plates, antenna mount and automatic
frequency control box being painted
installation consists of following parts:
RT-524A/VRC (1 ea.),
Mounting tray, MT-1029/VRC (1 ea.),
R-442A/VRC (1 ea.),
Mounting tray, MT-1898/VRC (1 ea.),
Mounting frames, (2 ea.),
Mounting plates, (2 ea.),
Antenna mounts, (2 ea.),
Antenna equipment AL-3 consisting of:
-- Automatic frequency control box, AM-30 (1 ea.),
-- Antenna base AB-129/PR (1 ea.),
-- Antenna, AM-31-1 (1 ea.),
Antenna base AB-15/GR (1 ea.),
Mast section, MS-116A, MS-117A, MS-118A (1 ea.),
Adapter, UG-273/U (1 ea.),
mount (left) and MT-1029/VRC
| Loudspeaker, LS-454/U (1 ea.),
Microphone, M-980DA (1 ea.),
Headset, H-251DA (1 ea.),
Control-box, retransmission, C-2299/VRC (1 ea.),
Mounting-bracket, C-2299/VRC (1 ea.),
Power supply box (1 ea.),
Cable, MK-100/3,6 (1 ea.),
Cable, MK-102/2,5 (1 ea.),
Cable, MK-105/1,0 (1 ea.),
Cable, MK-108/0,8 (2 ea.),
Cable, MK-115/0,8 (1 ea.),
Assorted bolts, washers, etc.
Frequency: 30.00 to 75.95 MHz.
MT-1898/VRC and antenna mount
Power Output: 35 W minimum @ 25.5
Vdc (high power); 0.5-10 W @ 30.0 ovde (low power).
(applicable to R-442A/VRC and receiver sections of RT-246A/VRC and RT-524A/VRC)
Sensitivity: 0.5 µV for
10 dB (S+N+D)/(N+D) for 8.0 kHz deviation.
Bandwidth: 32 kHz minimum @ 6 dB. 85 kHz maximum @ 60 dB.
Squelch: 150-Hz tone-operated or noise-operated, with RF signal having 10 dB (S+N+D)/(N+D) ratio.
Limiting: Less than 1 dB change in audio output for RF input from 1 µV to 100,000 µV.
Distortion: Less than 8% from 500 to 3000 Hertz.
Audio Output: 500 mW into 600-Ohm speaker 150 mW into 600-Ohm headphone.
Volume Control: Adjustable from less than 0.25 mW to 1.0 W maximum.
Power Requirement: 0.75 A @ 26.5 Vdc.
|C-2299/VRC mounted on bracket below the gear shift lever|
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